Method for gesture detection on a touchpad

ABSTRACT

In a gesture detection method for a touchpad, according to the present invention, various gestures such as tap, drag and double tap are determined by operating an object to touch on the touchpad, leave from the touchpad, and move on the touchpad.

FIELD OF THE INVENTION

The present invention is related generally to a detection method for a touchpad and, more particularly, to a method for gesture detection on a capacitive touchpad.

BACKGROUND OF THE INVENTION

Capacitive touchpad is an input device that allows user to slide his finger on a smooth panel thereof for cursor movement control. Because of its very small thickness, capacitive touchpad can be designed in slim notebooks, keyboards, digital media players and other devices, and moreover, due to its non-mechanical design it is virtually maintenance free.

FIG. 1 is a cross-sectional view of a conventional two-dimensional capacitive touchpad 100, which comprises a panel 102, a Y-axial sensing layer 104, an insulating layer 106, an X-axial sensing layer 108, and a bottom plate 110. When a finger 112 touches on the panel 102, the sensed value (in capacitance) on the touched position will varies, and the control circuit connected to the touchpad 100 can convert the capacitance on the touchpad 100 to a sensed value as shown in FIG. 2, by which the position where the finger 112 touches and the moving distance and the moving direction of the finger 112 can be determined. Conventionally, there are two methods to determine whether an object touches on the touchpad 100. In the first method, the sensed value on the touchpad 100 is used to determine if an object touches on the touchpad 100 by the way as shown in FIG. 3. When the sensed value is greater than a threshold th, it is determined that an object touches on the touchpad 100, and on the contrary, when the sensed value is less than the threshold th, it is determined that the object leaves the touchpad 100 or no object touches on the touchpad 100. In the second method, the cumulative sensed value on the touchpad 100 is used to determine if an object touches on the touchpad 100 by the way as shown in FIG. 4, by which, if the cumulative sensed value is greater than a threshold th, it is determined that an object touches on the touchpad 100, otherwise it is determined that the object leaves the touchpad 100 or no object touches on the touchpad 100. However, these two detection methods might be interfered by external noises, which will cause erroneous determination and accordingly operation that is not desired or predicted. Moreover, the operations of tape, drag, double tape and other gesture on the touchpad 100 are determined based on the time relationship when an object is operated to touch on the touchpad 100, leave from the touchpad 100, and move on the touchpad 100, and thus, for a user using the touchpad 100 first time or being unfamiliar with operating the touchpad 100, the action might not be so definite that the touchpad 100 will detect thereto incorrectly and cause inconvenient use.

Therefore, there is a need of a detection method for a touchpad that will avoid noise to interfere the operation of the touchpad and have the touchpad to be easy to operate therewith.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a gesture detection method for a touchpad for preventing the operation of the touchpad from noise interference.

In a gesture detection method for a touchpad, according to the present invention, various gestures such as tap, drag and double tap are determined by operating an object to touch on the touchpad, leave from the touchpad, and move on the touchpad.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a conventional two-dimensional capacitive touchpad;

FIG. 2 shows a relationship between the sensed value and the touched position of the touchpad shown in FIG. 1;

FIG. 3 shows a variation of the sensed value on the touchpad shown in FIG. 1;

FIG. 4 shows a variation of the cumulative sensed value on the touchpad shown in FIG. 1;

FIG. 5 shows a variation of the sensed value on the touchpad shown in FIG. 1 when the sensed value becomes greater than a down threshold;

FIG. 6 shows a difference between two sensed values shown in FIG. 5;

FIG. 7 shows a detected signal;

FIG. 8 shows a variation of the sensed value on the touchpad shown in FIG. 1 when the sensed value becomes less than a lift threshold;

FIG. 9 shows a difference between two sensed values shown in FIG. 8;

FIG. 10 shows a detected signal;

FIG. 11 shows a variation of the sensed value on the touchpad shown in FIG. 1 when an object moves from still to left side;

FIG. 12 shows a difference between two sensed values shown in FIG. 11;

FIG. 13 shows a detected signal and an output signal of an embodiment in a tap gesture;

FIG. 14 shows a detected signal and an output signal of an embodiment in a drag gesture;

FIG. 15 shows a detected signal and an output signal of another embodiment in a drag gesture;

FIG. 16 shows a detected signal and an output signal of an embodiment in a double tap gesture; and

FIG. 17 shows a detected signal and an output signal of another embodiment in a double tap gesture.

DETAILED DESCRIPTION OF THE INVENTION

In a detection method for a capacitive touchpad according to the present invention, the noise resistive capability of the touchpad is enhanced without any improvement on the hardware detection circuit of the touchpad, and several gestures for operations on the touchpad can be distinguished by such method.

<Detection for Verifying an Object Down>

In FIG. 5, it is shown a variation of the sensed value on the touchpad 100 of FIG. 1 when the sensed value becomes greater than a down threshold th, in which curve 200 represents the sensed value at this time and curve 202 represents the sensed value at the last time. FIG. 6 shows the difference between the sensed values 200 and 202 of FIG. 5, and FIG. 7 shows a detected signal 204. In a detection of the sensed value on the touchpad 100, when the sensed value is detected greater than the down threshold th as shown in FIG. 5, the detected signal 204 will transit from low to high as shown in FIG. 7, and then, within a reference time interval T_(DownDetect), the sensed value on the touchpad 100 is continuously detected and the differential sensed value dV is calculated by subtracting each current sensed value 202 by the last sensed value 200 as shown in FIG. 6. If the differential sensed value dV within the reference time interval T_(DownDetect) maintains positive, it is determined that an object touches down to the touchpad 100.

<Detection for Verifying an Object Lift>

FIG. 8 shows a variation of the sensed value on the touchpad 100 of FIG. 1 when the sensed value becomes less than a lift threshold th, in which curve 210 represents the sensed value at this time and curve 212 represents the sensed value at the last time, FIG. 9 shows the difference between the sensed values 210 and 212 of FIG. 8, and FIG. 10 shows a detected signal 214. After an object has touched on the touchpad 100, once the sensed value is detected less than the lift threshold th as shown in FIG. 8, the detected signal 214 will transit from high to low as shown in FIG. 10, and then, within a reference time interval T_(LiftDetect), the sensed value on the touchpad 100 is continuously detected and the differential sensed value dV is calculated by subtracting each current sensed value 210 by the last sensed value 212 as shown in FIG. 9. If the differential sensed value dV within the reference time interval T_(LiftDetect) maintains negative, it is determined that the object leaves from the touchpad 100.

<Detection for Verifying an Object Moving>

The variation of an object on the touchpad 100 from still to move is verified to avoid noise or slight vibration of the object to cause a misjudgment on the object position which will result in the corresponding cursor to have wrong action. FIG. 11 shows a variation of the sensed value on the touchpad 100 shown in FIG. 1 when an object on the touchpad 100 moves from still to left side, in which curve 220 represents the sensed value at this time and curve 222 represents the sensed value at the last time, and FIG. 12 shows the difference between the sensed values 220 and 222 shown in FIG. 11. After an object is verified to touch on the touchpad 100, the sensed value on the touchpad 100 is continuously detected and the differential sensed value dV is calculated by subtracting each current sensed value 220 by the last sensed value 222. Within a reference time interval T_(MovingDetect), if the left side of the object is detected to have the differential sensed value dV in an increasing trend and the right side of the object is detected to have the differential sensed value dV in a decreasing trend as shown in FIGS. 11 and 12, the object is determined to move from still to left side. On the contrary, within the reference time interval T_(MovingDetect), if the left side of the object is detected to have the differential sensed value dV in a decreasing trend and the right side of the object is detected to have the differential sensed value dV in an increasing trend, the object is determined to move from still to right side.

<Detection for a Tap Gesture>

FIG. 13 shows a detected signal 310 and an output signal 320 in a tap gesture, and the output signal 320 includes gesture signals 322 and 324. In response to an object touching down to the touchpad 100, the detected signal 310 transits from low to high. If the detection for verifying an object down confirms that the object indeed touches down to the touchpad 100, the object is further determined whether or not to move on the touchpad 100 according to the detection for verifying an object moving. If the object is determined to move on the touchpad 100, a moving gesture is determined; otherwise the detected signal 310 will transit from high to low thereafter when the object is determined to leave the touchpad 100 and then, if the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100, the gesture signal 322 (e.g., for a key-press signal) is initiated and the departure time is counted for the object to leave the touchpad 100. Further, if the departure time reaches a reference time interval T_(Tap), the gesture signal 324 (e.g., for a key-release signal) is produced to terminate the gesture signal 322.

<Detection for a Drag Gesture>

FIG. 14 shows a detected signal 330 and an output signal 340 in a drag gesture, and the output signal 340 includes gesture signals 342 and 344. When an object is detected to touch down to the touchpad 100 first time, the detected signal 330 transits from low to high, and if the detection for verifying an object down confirms that the object indeed touches down to the touchpad 100, the object is further determined whether or not to move on the touchpad 100 according to the detection for verifying an object moving. If the object is determined to move on the touchpad 100, a moving gesture is determined; otherwise the detected signal 330 will transit from high to low thereafter when the object is determined to leave the touchpad 100 and then, if the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100, the gesture signal 342 (e.g., for a key-press signal or for a key-press with zero-displacement signal) is initialized and the departure time is counted for the object to leave the touchpad 100. Further, if the touchpad 100 is detected to be touched again before the departure time reaches a reference time interval T_(Drag), the detected signal 330 transits from low to high again. After the detection for verifying an object down confirms that the touchpad 100 is indeed touched by an object again, the object is determined whether or not to move on the touchpad 100 according to the detection for verifying an object moving. If the object indeed moves on the touchpad 100, a position information of the object is calculated and the gesture signal 344 (e.g., for a combinational signal of a key-press with the position information) is produced. Until the object is detected to leave the touchpad 100, the detected signal 330 transits from high to low, and the gesture signal 344 is terminated when the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100. In another embodiment, as shown in FIG. 15, the output signal 340 includes gesture signals 342, 344 and 346. When the object is detected to leave the touchpad 100 for the second time, the detected signal 330 transits from high to low, and after the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100, the gesture signal 346 (e.g., for a key-release signal) is produced to terminate the gesture signal 344. Typically, a position information of an object on the touchpad 100 may have an absolute coordinate, a relative coordinate, or a relative displacement of the object. The absolute coordinate is referred to a coordinate value generated with a fixed position (e.g., the center or a corner of the touchpad 100) as the original point, the relative coordinate is referred to a coordinate value generated with a relative position (e.g., the position first touched by the object on the touchpad 100) as the original point, and the relative displacement is referred to a displacement relative to the original point.

<Detection for a Double Tap Gesture>

FIG. 16 shows a detected signal 350 and an output signal 360 in a double tap gesture, and the output signal 360 includes gesture signals 362, 364 and 366. When an object is detected to touch down to the touchpad 100 first time, the detected signal 350 transits from low to high, and if the detection for verifying an object down confirms that the object indeed touches down to the touchpad 100, the object is further determined whether or not to move on the touchpad 100 according to the detection for verifying an object moving. If the object is determined to move on the touchpad 100, a moving gesture is determined; otherwise the detected signal 350 will transit from high to low thereafter when the object is determined to leave the touchpad 100 and then, if the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100, the gesture signal 362 (e.g., for a key-press signal) is initialized and the departure time is counted for the object to leave the touchpad 100. Further, if the touchpad 100 is detected to be touched again before the departure time reaches a reference time interval T_(DoubleTap), the detected signal 330 transits from low to high again. After the detection for verifying an object down confirms that the touchpad 100 is indeed touched by an object again, the object is determined whether or not to move on the touchpad 100 according to the detection for verifying an object moving. If the object does not move on the touchpad 100, the detected signal 350 will transits from high to low again when the object is detected to leave from the touchpad 100 again, and after the detection for verifying an object lift confirms that the object indeed leaves the touchpad 100, the gesture signal 364 (e.g., for a key-release signal) is produced to terminate the gesture signal 362, followed with the gesture 366 (e.g., for a combinational signal of a key-press and a key-release). In another embodiment, as shown in FIG. 17, the output signal 360 includes gesture signals 362, 364, 368 and 370, and after the gesture signal 368 (e.g., for a key-press signal), the gesture signal 370 (e.g., for a key-release signal) is produced to terminate the gesture signal 368.

In the above embodiments, various gestures for operating on the touchpad 100 are confirmed with the variation of the sensed value and by determining whether or not the object moves on the touchpad 100, and therefore, in addition to avoid noise to interfere the operations of the touchpad 100, it is also avoided the disadvantage that the touchpad 100 can not determine the operation of indefinite actions, and the convenience of use is improved.

While the present invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and scope thereof as string forth in the appended claims. 

1. A method for gesture detection on a touchpad, comprising the steps of: verifying that an object touches on the touchpad; determining whether or not the object moves on the touchpad; verifying that the object leaves the touchpad if the object is determined not to move on the touchpad in the previous step; initiating a first gesture signal after the object is verified to leave the touchpad; counting a departure time after the object leaves the touchpad; and producing a second gesture signal after the departure time reaches a reference time interval; wherein the step of verifying that an object touches on the touchpad comprises the steps of: monitoring a sensed value on the touchpad; monitoring a variation of the sensed value when the sensed value is greater than a threshold; and determining that the object touches on the touchpad if the sensed value remains greater than the threshold within a second reference time interval and maintains a continuously increasing trend during the second reference time interval.
 2. The method of claim 1, wherein the step of determining whether or not the object moves on the touchpad comprises the steps of: monitoring a sensed value on the touchpad; monitoring a variation of the sensed value; and determining that the object moves on the touchpad if, during a third reference time interval, the sensed value maintains a continuously increasing trend in a first direction and a continuously decreasing trend in a second direction opposite to the first direction.
 3. The method of claim 1, wherein the step of verifying that the object leaves the touchpad comprises the steps of: monitoring a sensed value on the touchpad; monitoring a variation of the sensed value when the sensed value is less than a threshold; and determining that the object leaves the touchpad if the sensed value remains less than the threshold within a third reference time interval and maintains a continuously decreasing trend during the third reference time interval.
 4. The method of claim 1, wherein the first gesture signal comprises a key-press signal.
 5. The method of claim 1, wherein the second gesture signal comprises a key-release signal. 